Fluid simulations provide more comprehensive view of cellular-level dynamics in bone
Fluid simulations provide more comprehensive view of cellular-level dynamics in bone lead image
Osteocytes transform mechanical cues from surrounding bone into signals that direct bone development. This mechanotransduction, however, remains poorly understood at the cellular level.
Zhu et al. developed a model that considers how frequently neglected aspects affect fluid stresses on the osteocyte surface. The group used the lattice Boltzmann equations to study how number and geometry of the microscopic tunnels connecting osteocytes, called the lacuna-canalicular (LC) network, and proteins in the fluid surrounding the osteocytes, the pericellular matrix (PCM), affect fluid flow around an osteocyte.
“The study provides a leap forward in complexity for simulating an osteocyte’s LC network, a complex geometry that can have 60 or more irregular canaliculi and is often simplified to a handful of straight tubes that contain no PCM,” said author Luoding Zhu.
The model randomizes the prescribed incoming and outgoing flow to better capture the variations that can occur in real life.
“The study suggests that forces on osteocytes can vary on a case-to-case basis depending on the osteocyte and scenario being considered,” said co-author Jared Barber. “When averaged across many simulations, however, the mean stresses do not depend on the number or geometry of the canaliculi.”
The group found including PCM near the osteocyte, in the canaliculi or not, increased fluid forces on the osteocyte surface.
The stress on the osteocyte quantified after non-dimensionalization is inversely proportional to Reynolds number values. Increasing PCM density reduces the range of this effect.
The group aims to develop its model further. They hope their work encourages caution when extrapolating results from one-cell studies and stokes further interest in models that account for the PCM.
Source: “Modeling and simulation of interstitial fluid flow around an osteocyte in a lacuno-canalicular network,” by Luoding Zhu, Jared Barber, Robert Zigon, Sungsoo Na, and Hiroki Yokota, Physics of Fluids (2022). The article can be accessed at https://doi.org/10.1063/5.0085299 .
